Fuel barrier thermoplastic resin composition and shaped article

ABSTRACT

The thermoplastic resin composition of the invention comprises (A) 50 to 97% by weight of a polyolefin, (B) 2 to 45% by weight of a polyamide resin comprising a diamine component and a dicarboxylic acid component and (C) 1 to 45% by weight of a modified polyolefin and/or styrene copolymer. The polyamide resin is specified by that at least 70 mol % of the diamine component is a constitutional unit derived from m-xylylenediamine and at least 70 mol % of the dicarboxylic acid component is a constitutional unit derived from a C 4 -C 20  straight-chain α,ω-aliphatic dicarboxylic acid and isophthalic acid in a molar ratio of 3:7 to 10:0. With such a chemical component, the thermoplastic resin composition exhibits excellent fuel barrier properties, heat resistance and moldability.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermoplastic resin compositionexcellent in fuel barrier properties and its multi-layered shapedarticle, more particularly, relates to a thermoplastic resin compositionhaving a low fuel permeability, an excellent heat resistance andexcellent molding properties which is particularly suitable for thematerials for containers of alcohol-containing fuels, tubes and parts,and relates to a multi-layered shaped article made of such athermoplastic resin composition.

2. Description of the Prior Art

In view of lightweight, needlessness of anti-corrosive treatment, widedesign liberty, reduction in the number of processing steps, andcapability of full automatic production, resin containers formed by blowmolding, etc. have come to attract attention as the fuel storagecontainers and the replacement of metal fuel containers by resin fuelcontainers is now advancing.

However, since polyethylene (high density polyethylene) hitherto usedfor resin fuel containers is poor in the fuel barrier properties despiteits excellence in mechanical strength, moldability and economy, the fuelcontainers made of polyethylene cannot meet the recent regulations offuel permeation from fuel container.

To solve this problem, many proposals have been made on the preventionof the fuel permeation, for example, by a fluorine treatment of theinner surface of containers or a blending of polyamide resin topolyethylene (JP 55-121017A, JP 5-156036A and JP 10-279752). However,the fluorine treatment is now scarcely used because the use of harmfulgas requires safety precautions for its handling and troublesomerecovery of the harmful gas after treatment. By blending a barrier resininto polyolefin so as to disperse throughout polyethylene in laminar,the fuel permeation can be reduced to some extent. However, the fuelbarrier properties are sill unsatisfactory. If the addition amount ofthe barrier resin is increased, other problems are caused, for example,the absorption ability of crash impact is reduced and the moldabilitybecomes poor, thereby failing to fully meet the regulations which aregetting increasingly stringent. The use of alcohols such as ethanol as afuel has been progressively considered because the use of fossil fuelscan be reduced by adding alcohols into gasoline thereby to reduce thecarbon dioxide emission. However, since known barrier resins such asnylon 6 and ethylene-vinyl alcohol copolymers show poor barrierproperties against alcohols, a material having an enhanced barrierproperties is demanded.

SUMMARY OF THE INVENTION

An object of the invention is to solve the above problems involved inknown fuel containers and provide a thermoplastic resin compositionexcellent in the fuel barrier properties, heat resistance andmoldability and multi-layered shaped articles.

As a result of extensive research in view of achieving the above object,the inventors have found that a resin composition comprising (A)polyolefin, (B) polyamide resin having a specific constitutional monomerratio and (C) a modified polyolefin and/or styrene copolymer isexcellent in the fuel barrier properties, heat resistance andmoldability and suitable as the material for the production of fuelcontainers, tubes, parts, etc. The invention has been accomplished onthe basis of this finding.

Thus, the present invention provides a fuel barrier thermoplastic resincomposition comprising (A) 50 to 97% by weight of a polyolefin, (B) 2 to45% by weight of a polyamide resin comprising a diamine component and adicarboxylic acid component, at least 70 mol % of the diamine componentbeing a constitutional unit derived from m-xylylenediamine and at least70 mol % of the dicarboxylic acid component being a constitutional unitderived from a C₄-C₂₀ straight-chain α,ω-aliphatic dicarboxylic acid andisophthalic acid in a molar ratio of 3:7 to 10:0, and (C) 1 to 45% byweight of a modified polyolefin and/or styrene copolymer. The inventionfurther provides a multi-layered shaped article made by utilizing thethermoplastic resin composition.

The thermoplastic resin composition of the invention is excellent in thefuel barrier properties, heat resistance and moldability, and isapplicable to the production of various shaped articles such as fuelcontainers, tubes and parts.

DETAILED DESCRIPTION OF THE INVENTION

The polyolefin A used in the invention may be selected from variouspolymers, and preferably selected from homopolymers of ethylenichydrocarbon having two or more, preferably 2 to 8 carbon atoms such aslow density polyethylene, medium density polyethylene, high densitypolyethylene, linear low density polyethylene, polypropylene,1-polybutene and 1-polyemthylpentene; homopolymers of α-olefin having 3to 20 carbon atoms; copolymers of α-olefin having 3 to 20 carbon atomssuch as ethylene/propylene copolymers, ethylene/propylene/dieneterpolymers, ethylene/1-butene copolymers, ethylene/4-methyl-1-pentenecopolymers, ethylene/1-hexene copolymers, ethylene/1-octene copolymers,ethylene/1-decene copolymers, propylene/1-butene copolymers,propylene/4-methyl-1-pentene copolymers, propylene/1-hexene copolymers,propylene/1-octene copolymers and propylene/1-decene copolymers; andcopolymers of α-olefin having 3 to 20 carbon atoms and cyclic olefinsuch as norbornene. These polyolefins may be used alone or incombination of two or more. Among the above polyolefins, preferred areresins such as polyethylene, polypropylene and 1-polybutene and resinshaving a high glass transition point such as copolymers of α-olefin andcyclic olefin. The polyolefin A preferably has a melt flow rate of 0.01to 10 g/10 min when measured at 190° C. under 2.16 kgf load.

The blending amount of the polyolefin A is 50 to 97% by weight,preferably 60 to 95% by weight, and more preferably 65 to 92% by weighton the basis of the thermoplastic resin composition. If less than 50% byweight, the impact strength and the moldability will be reduced. Ifexceeding 97% by weight, the fuel barrier properties are unfavorablyreduced.

The modified polyolefin used as the component C may be selected fromgraft-modified products, which are widely used generally ascompatibilizers or adhesives, produced by modifying the polyolefinrecited above with an unsaturated carboxylic acid or its anhydride.Examples of the unsaturated carboxylic acids and their anhydridesinclude acrylic acid, methacrylic acid, α-ethylacrylic acid, maleicacid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalicacid, cloromaleic acid, butenylsuccinic acid and anhydrides of thepreceding carboxylic acids, with maleic acid and maleic anhydride beingpreferred. The modified polyolefin is produced by a graftcopolymerization of the polyolefin with the unsaturated carboxylic acidor its anhydride using a known method, for example, by melting thepolyolefin in an extruder, etc. and then copolymerizing the moltenpolyolefin with an added graft monomer, by copolymerizing the polyolefinmade into a solution with an added graft monomer, or by copolymerizingthe polyolefin made into a water suspension with an added graft monomer.

The styrene copolymer used as the component C may be selected fromstyrene block copolymers each comprising a hydrogenated block copolymerwhich is produced by partially or completely hydrogenating copolymer ofa vinyl aromatic compound and a conjugated diene compound. Examples ofthe conjugated diene compounds include 1,3-butadiene, 1,3-pentadiene andisoprene, with 1,3-butadiene being preferred. The styrene copolymer maybe modified by the unsaturated carboxylic acid or its anhydride.

The blending amount of the component C (modified polyolefin and/orstyrene copolymer) is 1 to 45% by weight, preferably 2 to 40% by weight,and more preferably 4 to 30% by weight on the basis of the thermoplasticresin composition. If less than 1% by weight, the affinity between thepolyolefin and the polyamide resin will be reduced to result in thereduction of the impact resistance. If exceeding 45% by weight, it willbecome difficult to allow the polyamide resin to be dispersed inlaminar.

The polyamide resin B is constituted by a diamine component in which atleast 70 mol % (inclusive of 100 mol %) is a constitutional unit derivedfrom m-xylylenediamine and a dicarboxylic acid component in which atleast 70 mol % (inclusive of 100 mol %) is a constitutional unit derivedfrom a C₄-C₂₀ straight-chain α,ω-aliphatic dicarboxylic acid andisophthalic acid in a molar ratio of 3:7 to 10:0.

The diamine component may include a constitutional unit derived fromdiamine other than m-xylylenediamine such as aliphatic diamines, forexample, tetramethylenediamine, pentamethylenediamine,hexamethylenediamine, octamethylenediamine and nonamethylenediamine;aromatic diamines, for example, p-phenylenediamine andp-xylylenediamine; and alicyclic diamines, for example,bis(aminomethyl)cyclohexane, in an amount of less than 30 mol % of thetotal diamine component.

The C₄-C₂₀ straight-chain α,ω-aliphatic dicarboxylic acid forconstituting the dicarboxylic acid component of the polyamide resin Bmay be selected from aliphatic dicarboxylic acids such as succinic acid,glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid,sebacic acid, undecanedioic acid and dodecanedioic acid, with adipicacid being preferred.

The dicarboxylic acid component of the polyamide resin B includes theconstitutional unit derived from the C₄-C₂₀ straight-chain α,ω-aliphaticdicarboxylic acid and isophthalic acid in a molar ratio of 3:7 to 10:0,preferably 3:7 to 9.5:0.5, and more preferably 4:6 to 8:2 in an amountof 70 mol % or more.

The dicarboxylic acid component may include a constitutional unitderived from dicarboxylic acid other than the C₄-C₂₀ straight-chainα,ω-aliphatic dicarboxylic acid and isophthalic acid, for example,aliphatic dicarboxylic acid such as azelaic acid and sebacic acid;monocarboxylic acids such as benzoic acid, propionic acid and butyricacid; polybasic carboxylic acids such as trimellitic acid andpyromellitic acid; and carboxylic anhydrides such as trimelliticanhydride and pyromellitic anhydride in an amount of less than 30 mol %of the total dicarboxylic acid component.

When the unit derived from isophthalic acid is included in the abovemolar range, the fuel barrier properties, particularly the barrierproperties against fuels containing methanol, ethanol, etc. may befurther improved. In addition, as compared with the sole use of theC₄-C₂₀ straight-chain α,ω-aliphatic dicarboxylic acid, the resultantpolyamide resin has a lower melting point, this enabling the molding atlower temperatures to reduce the production energy and shorten themolding cycle, and has a higher melt viscosity, this improving themoldability by preventing draw down.

The polyamide resin B may include constitutional units derived fromlactams such as ε-caprolactam, ω-laurolactam and ω-enantolactam; andamino acids such as 6-aminocaproic acid, 7-aminoheptanoic acid,11-aminoundecanoic acid, 12-aminododecanoic acid, 9-aminononanoic acidand p-aminomethylbenzoic acid, in an amount not adversely affecting theeffect of the invention.

The polyamide resin B is produced by a known method, for example, bymelt-polycondensing the diamine component containing m-xylylenediaminein an amount of 70 mol % or more and the dicarboxylic acid componentcontaining the C₄-C₂₀ straight-chain α,ω-aliphatic dicarboxylic acid andisophthalic acid in a molar ratio of 3:7 to 10:0 in an amount of 70 mol% or more. For example, a nylon salt of m-xylylenediamine and adipicacid or a nylon salt of m-xylylenediamine, adipic acid and isophthalicacid is allowed to polymerize in a molten state by heating underpressure in the presence of water while removing the water added and thewater generated with the progress of polycondensation. Alternatively,the polycondensation may be conducted by adding m-xylylenediaminedirectly into a molten adipic acid or a molten mixture of adipic acidand isophthalic acid under atmospheric pressure. In thispolycondensation, to prevent the solidification of the reaction system,the polycondensation is carried out by increasing the temperature of thereaction system so as to maintain the reaction temperature above themelting points of oligoamide and polyamide being produced whilecontinuously adding m-xylylenediamine.

The relative viscosity of the relatively low-molecular weight polyamideproduced by the melt polymerization is preferably 2.28 or less whenmeasured on a solution of one gram of polyamide resin in 100 mL of a 96%sulfuric acid. When the relative viscosity after the melt polymerizationis 2.28 or less, the resultant polyamide has a high quality with littlegel-like substances and little discoloration. However, the viscosity issometimes low for the production of films, sheets and the multi-layeredshaped articles such as bottles. In this case, the viscosity may beincreased by solid polymerization of the polyamide produced by the meltpolymerization, etc. When isophthalic acid is used in the above range,the melt viscosity is increased and the melting point is lowered.Therefore, the molding temperature (from melting point +10° C. tomelting point +30° C., but from 180+10° C. to 180+30° C. for amorphouspolymer) can be reduced while ensuring a sufficient melt viscosity atthe molding temperature. Thus, the use of isophthalic acid can eliminatethe step for increasing the viscosity by solid polymerization, etc. andmake the production economically advantageous.

The melting point of the polyamide resin B is preferably 160 to 240° C.,more preferably 170 to 230° C. By bringing the melting point of thepolyamide resin B close to those of the other thermoplastic resins (thepolyolefin A and the component C), the molding defects such as uneventhickness due to the difference between the molding temperatures optimumfor the resins and the generation of odor and discoloration due to thedegradation of resins can be avoided during the production ofmulti-layered shaped articles.

The melt viscosity of the polyamide B is preferably 1000 to 5000 Pa·s,more preferably 1500 to 4000 Pa·s when measured at the moldingtemperature under a shear rate of 100 s⁻¹. By regulating the meltviscosity within the above range, the occurrence of draw down and thereduction of mechanical strength can be prevented during the productionof multi-layered shaped articles by blow molding. Polyamide resin havinga melt viscosity of higher than 5000 Pa·s is difficult to produce.

The glass transition point of the polyamide resin B is preferably 80 to130° C. By regulating the glass transition point to 80° C. or higher,excellent fuel barrier properties at high temperatures are achieved.

The blending amount of the polyamide resin B is 2 to 45% by weight,preferably 3 to 30% by weight, and more preferably 5 to 20% by weight.If less than 2% by weight, the fuel barrier properties will be poor, andthe impact resistance will be reduced if exceeding 45% by weight.

The thermoplastic resin composition of the invention may optionallycontain (D) a smectite treated with an organic swelling agent (smectiteD). The smectite is dioctahedral type or trioctahedral typephyllosilicate having an electric charge density of 0.25 to 0.6.Examples of the dioctahedral type phyllosilicates includemontmorillonite and beidellite. Examples of the trioctahedral typephyllosilicates include hectorite and saponite. Of thesephyllosilicates, preferred is montmorillonite.

The smectite treated with an organic swelling agent referred to hereinis a phyllosilicate having its interlaminar spacing spread before use bycontacting the phyllosilicate with the organic swelling agent such ashigh-molecular compounds and organic compounds.

The organic swelling agent is selected preferably from quaternaryammonium salts, more preferably from quaternary ammonium halide such aschloride and bromide, and still more preferably quaternary ammoniumsalts having at least one alkyl or alkenyl group having 12 or morecarbon atoms.

Examples of the organic swelling agents include trimethylalkylammoniumsalts such as trimethyldodecylammonium salts,trimethyltetradecylammonium salts, trimethylhexadecylammonium salts,trimethyloctadecylammonium salts and trimethyleicosylammonium salts;trimethylalkenylammonium salts such as trimethyloctadecenylammoniumsalts and trimethyloctadecadienylammonium salts; triethylalkylammoniumsalts such as triethyldodecylammonium salts, triethyltetradecylammoniumsalts, triethylhexadecylammonium salts and triethyloctadecylammoniumsalts; tributylalkylammonium salts such as tributyldodecylammoniumsalts, tributyltetradecylammonium salts, tributylhexadecylammonium saltsand tributyloctadecylammonium salts; dimethyldialkylammonium salts suchas dimethyldidodecylammonium salts, dimethylditetradecylammonium salts,dimethyldihexadecylammonium salts, dimethyldioctadecylammonium salts anddimethylditallowammonium salts; dimethyldialkenylammonium salts such asdimethyldioctadecenylammonium salts and dimethyldioctadecadienylammoniumsalts; diethyldialkylammonium salts such as diethyldidodecylammoniumsalts, diethylditetradecylammonium salts, diethyldihexadecylammoniumsalts and diethyldioctadecylammonium salts; dibutyldialkylammonium saltssuch as dibutyldidodecylammonium salts, dibutylditetradecylammoniumsalts, dibutyldihexadecylammonium salts and dibutyldioctadecylammoniumsalts; methylbenzyldialkylammonium salts such asmethylbenzyldihexadecylammonium salts; dibenzyldialkylammonium saltssuch as dibenzyldihexadecylammonium salts; trialkylmethylammonium saltssuch as tridodecylmethylammonium salts, tritetradecylmethylammoniumsalts and trioctadecylmethylammonium salts; trialkylethylammonium saltssuch as tridodecylethylammonium salts; trialkylbutylammonium salts suchas tridodecylbutylammonium salts; and co-amino acids such as4-amino-n-butyric acid, 6-amino-n-caproic acid, 8-aminocaprylic acid,10-aminodecanoic acid, 12-aminododecanoic acid, 14-aminotetradecanoicacid, 16amino-hexadecanoic acid and 18amino-octadecanoic acid. Inaddition, ammonium salts having a hydroxyl group and/or an ether groupmay also be used as the organic swelling agent. Examples thereof includemethyl dihydroxyethyl hydrogenated tallow ammonium salts and quaternaryammonium salts containing at least one alkylene glycol residue such asmethyldialkyl(PAG)ammonium salts, ethyldialkyl(PAG)ammonium salts,butyldialkyl(PAG)ammonium salts, dimethylbis(PAG)ammonium salts,diethylbis(PAG)ammonium salts, dibutylbis(PAG)ammonium salts,methylalkylbis(PAG)ammonium salts, ethylalkylbis(PAG)ammonium salts,butylalkylbis(PAG)ammonium salts, methyltri(PAG)ammonium salts,ethyltri(PAG)ammonium salts, butyltri(PAG)ammonium salts andtetra(PAG)ammonium salts wherein the “alkyl” represents an alkyl grouphaving 12 or more carbon atoms such as dodecyl, tetradecyl, hexadecyl,octadecyl and eicosyl; and PAG represents a polyalkylene glycol residue,preferably a polyethylene glycol residue or a polypropylene glycolresidue having 20 carbon atoms or less. Of these organic swellingagents, preferred are trimethyldodecylammonium salts,trimethyltetradecylammonium salts, trimethylhexadecylammonium salts,trimethyloctadecylammonium salts, dimethyldidodecylammonium salts,dimethylditetradecylammonium salts, dimethyldihexadecylammonium salts,dimethyldioctadecylammonium salts, dimethylditallowammonium salts andmethyl dihydroxyethyl hydrogenated tallow ammonium salts. These organicswelling agents may be used alone or in combination of two or more.

The blending amount of the smectite D is preferably 0.3 to 20 parts byweight and more preferably 1 to 15 parts by weight based on 100 parts byweight of the polyamide resin B. When used 0.3 part by weight or higher,the fuel barrier properties can be further improved. A blending amountexceeding 20% by weight creates no additional effect on improving thebarrier properties.

The smectite D is preferably mixed with the polyamide resin B to form aresin composition which is then blended with the polyolefin A and thecomponent C (modified polyolefin and/or styrene copolymer). The smectiteD should be uniformly dispersed throughout the polyamide resin B withoutlocally forming agglomerates. The uniform dispersion referred to hereinmeans that the layers of phyllosilicate in the polyamide resin isseparated into flat plates, 50% or more of which are spaced at aninterlaminar spacing of 5 nm or more. The interlaminar spacing means adistance between the gravity centers of flat plates. The larger theinterlaminar spacing, the smectite D is dispersed more uniformly to givethe final film, sheet and hollow container having a good appearance suchas transparency and an improved barrier property to gaseous substancessuch as oxygen and carbon dioxide gas.

The smectite D is melt-kneaded with the polyamide resin B by knownmethods, for example, by a method in which the smectite D is added understirring during the melt-polymerization for producing the polyamideresin B, a method in which the smectite D and the polyamide resin B aremelt-kneaded in various general extruders such as single-screw ortwin-screw extruders, etc., with the melt-kneading method using atwin-screw extruder being preferred in view of productivity andflexibility.

The melt-kneading is preferably performed by using a screw having atleast one reverse flighted element and/or kneading disk for forming adwelling zone and allowing the polyamide resin B and the smectite D tobe partly retained at each dwelling zone, while controlling themelt-kneading temperature to 180 to 260° C. and the residence time to 5min or less.

Melt-kneading temperatures outside the above range are likely to cause apoor dispersion of the smectite D. The dwelling zone of the screwimproves the dispersion of the smectite D. In view of a gooddispersibility and the prevention of thermal decomposition and gelformation, the melt-kneading time is preferably 1 to 5 min.

The polyamide resin B containing or without containing the smectite D ispreferably made into pellets before blended with the polyolefin A andthe component C. To enhance the compatibility with the polyolefin A andincreasing the mechanical strength of resultant multi-layered shapedarticles, the pellets are preferably made into a multi-layeredstructure, for example, comprising an outer layer of the modifiedpolyolefin and an inner layer of the polyamide resin B. In suchmulti-layered pellets, the weight ratio of the modified polyolefin andthe polyamide resin B is preferably 95:5 to 5:95.

The thermoplastic resin composition may be prepared by a known method,for example, by kneading the polyolefin A, the polyamide resin B and thecomponent C (modified polyolefin and/or styrene copolymer) or kneadingthe polyolefin A with the multi-layered pellets of the polyamide resin Band the component C as described above in an extruder, etc., and thenextruding at 180 to 250° C. When the smectite treated with an organicswelling agent (smectite D) is used, it is preferred to produce thethermoplastic resin composition by kneading the pellets of the smectiteD and the polyamide resin B prepared in advance with the polyolefin Aand the component C.

The multi-layered shaped article of the invention preferably has alaminate structure comprising at least one high barrier layer made ofthe thermoplastic resin composition of the invention and at least onereinforcing layer made of polyolefin, polystyrene, polyester,polycarbonate or polyamide. Examples of the polyolefin include linearlow-density polyethylene, low-density polyethylene, medium-densitypolyethylene, high-density polyethylene, ultrahigh-molecular,high-density polyethylene, polypropylene, copolymers of at least twoolefins selected from ethylene, propylene, butene, etc., and mixturesthereof. Of these polyolefins, the ultrahigh-molecular, high-densitypolyethylene is preferred in view of the prevention of draw down in blowmolding process and its excellence in impact resistance, fuel-swellingresistance and water resistance. The polyolefins, polystyrenes,polyesters, polycarbonates and polyamides for the reinforcing layer maybe mixed with each other, or may be mixed with another resin such aselastomers or with various additives such as carbon black and flameretardants.

Between the layers of the multi-layered shaped article, for example,between the high barrier layer made of the thermoplastic resincomposition of the invention and the reinforcing layer, a adhesive resinlayer (adhesive layer) may be disposed. As the adhesive resin, modifiedpolyethylenes, modified polypropylenes and copolymers of olefins such asethylene, propylene and butene are usable when the high barrier layermade of the thermoplastic resin composition of the invention isadhesively bonded to the reinforcing layer made of polyolefin; andethylene-vinyl acetate copolymers, alkali or alkaline earthmetal-crosslinked ethylene-acrylic acid copolymers and ethylene-acrylicester copolymers are usable when the high barrier layer made of thethermoplastic resin composition of the invention is adhesively bonded tothe reinforcing layer made of polyester or polycarbonate, although notparticularly limited thereto.

The thickness of each layer depends on the shape of the multi-layeredshaped article, and preferably, 0.005 to 5 mm in average for the highbarrier layer made of the thermoplastic resin composition, 0.005 to 10mm in average for the reinforcing layer and 0.005 to 5 mm in average forthe adhesive layer.

The flash and molding defect may be re-melted and recycled as a recyclelayer of the multi-layered shaped article. The recycle layer ispreferably disposed outside the high barrier layer made of thethermoplastic resin composition in view of mechanical strength.

Each layer of the multi-layered shaped article of the invention mayoptionally contain lubricant, mold-release agent, antioxidant,processing stabilizer, heat stabilizer, ultraviolet absorber,phyllosilicate, nucleating agent or inorganic or organic metal salt orcomplex of Co, Mn, Zn, etc., unless the addition thereof adverselyaffects the objects of the invention.

The multi-layered shaped article of the invention includes multi-layeredcontainers in the form of bottle, cup, tray and tank, multi-layeredtube, multi-layered parts, etc. each comprising a laminate comprising atleast one high barrier layer made of the thermoplastic resincomposition, at least one reinforcing layer and at least one optionaladhesive layer. The multi-layered shaped article may be produced by amelt molding method such as multi-layer extrusion, extrusion followed bythermoforming and blow molding or a co-injection molding method such assandwich forming and two-color injection molding, although notspecifically limited thereto. More specifically, the multi-layeredshaped article is produced by a method in which a multi-layered sheetformed by a T-die extruder is thermoformed and then bonded by adhesiveor welding; a method in which a multi-layered cylindrical parison froman injection molding machine or an extrude is blow-molded; or aco-injection molding method in which two more kinds of molten resins aresequentially injected into a mold cavity.

The present invention will be explained in more detail by reference tothe following example which should not be construed to limit the scopeof the present invention. In the followings, the polyamide resins andthe multi-layered shaped articles were evaluated by the followingmethods.

(1) End Amino Concentration of Polyamide Resin

Accurately weighed polyamide (0.3 to 0.5 g) was dissolved in 30 mL of amixed solvent, phenol/ethanol=4/1 by volume, at 20 to 30° C. understirring. The end amino concentration was determined by neutralizationtitration of the resulting complete solution with a 1/100 N hydrochloricacid using an automatic titration device available from MitsubishiChemical Corp.

(2) End Carboxyl Concentration of Polyamide Resin

Accurately weighed polyamide (0.3 to 0.5 g) was dissolved in 30 mL ofbenzyl alcohol at 160 to 180° C. with stirring in a nitrogen flow. Theresulting complete solution was cooled to 80° C. or lower in a nitrogenflow and mixed with 10 mL of methanol under stirring. The end carboxylconcentration was determined by neutralization titration with a 1/100 Nsodium hydroxide aqueous solution using an automatic titration deviceavailable from Mitsubishi Chemical Corp.

(3) Reaction Molar Ratio of Polyamide Resin

Calculated from end amino concentration and end carboxyl concentrationaccording to the following formula:Reaction Molar Ratio=(1−18.015×[NH₂]−73.07×A)/(1−18.015×[COOH]+68.10×A),wherein [NH₂] is end amino concentration, [COOH] is end carboxylconcentration, and A is [COOH]−[NH₂].

(4) Relative Viscosity of Polyamide Resin

Accurately weighed one gram of polyamide resin was dissolved in 100 mLof 96% sulfuric acid at 20 to 30° C. under stirring. Immediately aftercomplete dissolution, 5 mL of the resulting solution was placed in aCanon Fenske viscometer, and the viscometer was allowed to stand in athermostatic chamber maintained at 25±0.03° C. for 10 min. Then, adropping time (t) of the solution was measured. Also, a dropping time(t₀) of the 96% sulfuric acid was measured. The relative viscosity wascalculated from the measured t and t₀ according to the followingformula:Relative Viscosity=t/t ₀.(5) Water Content

Measured at melting point −5° C. for 50 min in a nitrogen atmosphere bya trace water content meter “CA-05” available from Mitsubishi ChemicalCorp.

(6) Melting Point of Polyamide Resin

Measured at a temperature rise rate of 10° C./min using a heat fluxdifferential scanning calorimeter available from Shimadzu Corporation.

(7) Melt Viscosity of Polyamide Resin

Measured at a resin temperature of 210° C. and a shear rate of 100 sec⁻¹using Capirograph 1C (L/D of capillary: 10/1) available from Toyo SeikiSeisaku-Sho, Ltd. However, MX Nylon was measured at 260° C.

(9) Fuel Permeation

The raw materials were dry-blended in the blending ratios as shown inTable 1 or 2 to prepare each thermoplastic resin composition which wasthen made into a 400-mL container of about 120 g having an average wallthickness of 2 mm by a single-screw blow molding machine. The containerwas filled with 300 mL of fuel (isooctane/toluene/ethanol=45/45/10 byvolume) and sealed. The fuel-filled container was allowed to stand in anexplosion-proof type constant temperature/humidity chamber kept underconditions of 40° C./65% RH for 30 days. The change of weight was takenas the fuel permeation.

(10) Impact Resistance of Film

The raw materials were dry-blended in the blending ratios as shown inTable 1 or 2 to prepare each thermoplastic resin composition which wasthen made into a film of 200 μm thick by a labo-plastomill extruder. Theenergy at puncture of the film was measured under conditions of 23°C./50% RH by pushing a ½ inch ball against the film using a film impacttester ITF-60 available from ORIENTEC Co., Ltd.

EXAMPLE 1

Into a jacketed 50-L reaction vessel equipped with a stirrer, a partialcondenser, a cooler, a dropping tank and a nitrogen inlet, were charged7 kg (47.89 mol) of adipic acid and 3.4 kg (20.53 mol) of isophthalicacid. The inner atmosphere was fully replaced with nitrogen, and thecontents were made into a uniform slurry of isophthalic acid and moltenadipic acid at 160° C. in a small stream of nitrogen. To the slurry, wasadded dropwise 9.2 kg (67.29 mol) of m-xylylenediamine over 170 minunder stirring. During the addition, the inner temperature wascontinuously raised to 247° C. The water which was produced as theaddition of m-xylylenediamine proceeded was removed from the reactionsystem through the partial condenser and the cooler. After completion ofadding m-xylylenediamine, the inner temperature was raised to 260° C.and the reaction was continued for one hour. The resultant polymer wastaken out of the reaction vessel in the form of strand through a lowernozzle, water-cooled and then cut into pellets to obtain Polyamide 1.After vacuum-drying at 80° C. for 72 h, the properties of Polyamide 1were measured in the manners described above. The results are shown inTable 1.

Then, Polyamide 1 (polyamide resin B) was blended with a high densitypolyethylene “Novatech HB-431” (Japan Polyethylene Corporation; MFR=0.35g/10 min at 190° C. under 2160 gf load) as the polyolefin A and amodified polyethylene “Admer GT6” (Mitsui Chemicals, Inc.) as thecomponent C in respective blending ratios as shown in Table 2. The blendwas extruded at 200° C. to obtain a thermoplastic resin composition,which was then measured for the fuel permeation and the impactresistance. The results are shown in Table 2.

EXAMPLE 2

In the same manner as in Example 1 except for using 11.9 kg (81.65 mol)of adipic acid and adding dropwise 13.7 kg (100.739 mol) ofm-xylylenediamine over 160 min under stirring, Polyamide 2 was produced.The results of evaluation of the properties of Polyamide 2 are shown inTable 1.

Polyamide 2 was blended with the high density polyethylene and themodified polyethylene in respective blending ratios as shown in Table 2.The blend was extruded at 210° C. to obtain a thermoplastic resincomposition, which was then measured for the fuel permeation and theimpact resistance. The results are shown in Table 2.

EXAMPLE 3

A dry blend of 97 parts by weight of the Polyamide 1 and 3 parts byweight of montmorillonite (“Orben” tradename of Shiraishi Kogyo Co.,Ltd.) was fed at a rate of 12 kg/h from a metering feeder into atwin-screw extruder of a cylinder diameter of 37 mm equipped with astrong knead screw having a dwelling zone formed by a reverse flightedelement. The blend was melt-kneaded under conditions of a cylindertemperature of 200° C., a screw rotation speed of 500 rpm and a dwellingtime of 75 s. The molten strand from the extruder was cooled by coolingair, solidified and then pelletized to obtain Resin Composition 1. Theresults of evaluation of the properties of Resin Composition 1 are shownin Table 1.

In the same manner as in Example 1 except for using Resin Composition 1in place of Polyamide 1, a thermoplastic resin composition was preparedand the fuel permeation and the impact resistance were measured. Theresults are shown in Table 2.

EXAMPLE 4

The same procedure of Example 1 was repeated except for using Polyamide3 (poly(m-xylylenediadipamide) “MX Nylon S6121” tradename of MitsubishiGas Chemical Company, Inc.; melt viscosity (Pa·s)=2000) and producingthe thermoplastic resin composition by extruding at 240° C. The resultsof measurements of the fuel permeation and the impact resistance areshown in Table 2.

TABLE 1 Resin Polyamide 1  Polyamide 2 Composition 1 End amino 57 55 58concentration (μequiv/g) End carboxyl 109 102 134 concentration(μequiv/g) Reaction molar ratio 0.993 0.994 0.990 Relative viscosity(η_(r)) 1.73 1.90 1.75 Water content (%) 0.08 0.05 0.08 Melting point (°C.) 185 207 185 Melt viscosity (Pa · s) 2300 2000 2100

TABLE 2 Examples 1 2 3 4 Polyolefin A High density polyethylene (wt %)70 80 80 85 Polyamide Resin B Polyamide 1 (wt %) 15 — — — Polyamide 2(wt %) — 10 — — Polyamide 3 (wt %) — — — 5 Resin Composition 1 (wt %) —— 10 — Component C Modified polyethylene (wt %) 15 10 10 10 EvaluationResults Resistance to impact puncture (J) 1.7 1.9 1.9 1.9 Fuelpermeation (g) 1 2 1 2

COMPARATIVE EXAMPLE 1

The same procedure of Example 1 was repeated except for using Polyamide4 (nylon 6 “Ube Nylon 1030B” trademane of Ube Industries, Ltd.) andproducing the thermoplastic resin composition by extruding at 220° C.The results of measurements of the fuel permeation and the resistance toimpact puncture are shown in Table 3.

COMPARATIVE EXAMPLE 2

The same procedure of Example 1 was repeated except for using onlyNovatech HB-431. The results of measurements of the fuel permeation andthe resistance to impact puncture are shown in Table 3.

TABLE 3 Comparative Examples 1 2 Polyolefin A High density polyethylene(wt %) 80 100 Polyamide Resin B Polyamide 4 (wt %) 10 — Component CModified polyethylene (wt %) 10 — Evaluation Results Resistance toimpact puncture (J) 1.9 2.0 Fuel permeation (g) 8 18

As described above, the thermoplastic resin composition of the inventionis excellent in the fuel barrier properties, heat resistance andmoldability, and suitably applicable to various shaped articles such asfuel storage containers, tubes and parts.

1. A fuel-barrier thermoplastic resin composition comprising (A) 50 to97% by weight of a polyolefin, (B) 2 to 45% by weight of a polyamideresin comprising a diamine component and a dicarboxylic acid component,at least 70 mol % of the diamine component being a constitutional unitderived from m-xylylenediamine and at least 70 mol % of the dicarboxylicacid component being a constitutional unit derived from a C₄-C₂₀straight-chain α,ω-aliphatic dicarboxylic acid and isophthalic acid in amolar ratio of 4:6 to 8:2, and (C) 1 to 45% by weight of a modifiedpolyolefin and/or styrene copolymer.
 2. The fuel-barrier thermoplasticresin composition according to claim 1, further comprising (D) asmectite treated with an organic swelling agent, which is dispersed inthe polyamide resin B in an amount of 1 to 20 parts by weight on thebasis of 100 parts by weight of the polyamide resin B.
 3. Thefuel-barrier thermoplastic resin composition according to claim 1,wherein the polyamide resin B has a melting point of 160 to 207° C. 4.The fuel-barrier thermoplastic resin composition according to claim 1,wherein the polyamide resin B has a melt viscosity of 1000 to 5000 Pa·swhen measured at a molding temperature under a shear rate of 100 sec⁻¹.5. The fuel-barrier thermoplastic resin composition according to claim1, wherein the polyamide resin B is produced by melt-polymerizing adiamine component containing at least 70 mol % of m-xylylenediamine anda dicarboxylic acid component containing at least 70 mol % of a C₄-C₂₀straight-chain α,ω-aliphatic dicarboxylic acid and isophthalic acid in amolar ratio of 4:6 to 8:2.
 6. The fuel-barrier thermoplastic resincomposition according to claim 1, which is made into at least one layerforming a multi-layered shaped article.
 7. The fuel-barrierthermoplastic resin composition according to claim 1, wherein themodified polyolefin is a graft-modified product produced by modifying apolyolefin with an unsaturated carboxylic acid or its anhydride.
 8. Thefuel-barrier thermoplastic resin composition according to claim 7,wherein said graft-modified product is produced by modifying saidpolyolefin with maleic acid or maleic anhydride.
 9. The fuel-barrierthermoplastic resin composition according to claim 1, wherein thepolyamide resin B has a glass transition point of 80° C. to 130° C. 10.The fuel-barrier thermoplastic resin composition according to claim 1,wherein said polyolefin A, said polyamide resin B, and said modifiedpolyolefin and/or styrene copolymer C are blended together in saidcomposition.
 11. The fuel-barrier thermoplastic resin compositionaccording to claim 2, wherein said polyolefin A, said polyamide resin B,said modified polyolefin and/or styrene copolymer C, and said smectite Dare blended together in said composition.
 12. The fuel-barrierthermoplastic resin composition according to claim 11, which is madeinto at least one layer forming a multi-layered shaped article.
 13. Thefuel-barrier thermoplastic resin composition according to claim 10,which is made into at least one layer forming a multi-layered shapedarticle.
 14. The fuel-barrier thermoplastic resin composition accordingto claim 1, wherein the amount of said modified polyolefin and/orstyrene copolymer C included in the composition is 2-40% by weight. 15.The fuel-barrier thermoplastic resin composition according to claim 1,wherein the amount of said modified polyolefin and/or styrene copolymerC included in the composition is 4-30% by weight.
 16. The fuel-barrierthermoplastic resin composition according to claim 15, wherein theamount of said polyamide resin B in the composition is 5-20% by weight.17. The fuel-barrier thermoplastic resin composition according to claim16, wherein the amount of said polyolefin resin A in the composition is65-92% by weight.